Search for Highly Absorbable Negative Cosmic-Ray Particles at Sea Level

Abstract

A search has been made at sea level for negative cosmic-ray particles (other than electrons) which are absorbed in 147 g/${\mathrm{cm}}^2$ of lead and which have momenta greater than that of mu mesons of this range. The momentum and sign of the charge of those particles stopping in the absorber were determined by means of a counter controlled cloud chamber operated in a magnetic field. During 1400 hours of operation no negatively charged particle in the momentum interval 0.4-1.7 Bev/c was recorded as stopping in the absorber. This result has been used to show that the intensity of negative particles with strong nuclear interaction cannot amount to as much as 0.05 percent of the total intensity of negative particles in this momentum interval. It has been shown that the local production of negative mu mesons in the momentum interval 0.5-1.0 Bev/c is less than 8.8×${10}^{-5\mathrm{}}$ particle/(${\mathrm{cm}}^2$ steradian hr meter). A lower limit of 6.9×${10}^5$ g/${\mathrm{cm}}^2$ of lead has been set on the removal path length of mu mesons in the momentum interval 0.4-1.6 Bev/c.